Design of temperature control based fuzzy logic for substrate in thermophilic hydrogen reactor

Hydrogen can be produced from biomass using dark fermentation process. Dark fermentation is a way to produce hydrogen using anaerobic bacteria, grown in the dark on carbohydrate-rich substrates where their live cycles naturally produce H2 as metabolism byproduct. It is well known that hydrogen yield is affected by environmental factors such as temperature. It is reported that dark fermentation in thermophilic temperature that range from 40 - 65 °C is more efficient. Hydrogen production using dark fermentation in thermophilic temperature needs a heating system to set substrate at required temperature. After reaching thermophilic temperature, it is also important to keep a constant temperature during the digestion process, as temperature fluctuations of 1°C will affect the biogas production negatively. In this study, rice is used as biomass substrate. To control substrate temperature, thermophilic hydrogen production reactor is equipped with hot water jacket surrounding the reactors and using fuzzy logic as its control system. Fuzzy logic is used to set substrate temperature according to the set point. Substrate temperature set point is 55°C. From experiment, it is known that heating system could set substrate in thermophilic temperature range and able to control substrate temperature in 55°C with error mean 0.017°C.